Sean Mahoney resigned from the RNC in protest last month and is launching a bid for Congress in New Hampshire.

(CNN) - The former Republican National Committee member who resigned his post in protest after a high-profile spending scandal is embarking on a run for Congress in New Hampshire – and he's attacking his own party in the process.

Though his entry into the race against Democratic Rep. Carol Shea-Porter was expected, Portsmouth businessman Sean Mahoney officially joined the crowded GOP field on Monday with a Web video attacking not just Shea-Porter, but also the Republican Party that he claims "abandoned" him.

Mahoney, who resigned from the RNC earlier this month, is seen in the video giving a speech to Granite State Republicans.

"I'm not here to just cast aspersions on the Democrats," he says in the video, "because quite frankly, I'm a member of the Republican Party. But the Republicans are just as to blame for some of the mess we're in right now. Over the last 10 years, my Republican Party abandoned me as a conservative."